Pre-filled syringes that are filled with a selected dosage of a medication are well known injection devices for administering the medication to a patient. Safety devices for covering a needle of a pre-filled syringe before and after use are also well known. Typically, these devices comprise a needle shield that is either manually moved or moved by the action of a relaxing spring to surround the needle.
A different type of safety device known in the state of the art achieves the object of providing needle safety by arranging the pre-filled syringe movable relative to a body, where the pre-filled syringe is retracted into the body after the injection.
WO 2010/104779 A1 discloses a pharmaceutical delivery apparatus with an automatic syringe reaction following a manually controlled injection. The apparatus includes a housing, a syringe carriage, a medication-filled syringe held within the carriage, the syringe needle tip being disposed within the housing in a first position and projecting from the housing beyond the housing proximal end for insertion into an injection site in a second position, a manually shift table plunger, means on the carriage and the housing and the plunger for causing the carriage to advance from the first position to the second position and for injecting medicine from the syringe when the plunger is manually plunged proximally toward the housing, and means on the carriage and the plunger for causing the carriage to retract from the second position to a position at which the needle tip is disposed within the housing when the ;plunger shifts distally.